26 - 35 The age when you got married, realised it isn't what you thought it would be and start buying expensive toys?
actually, I think it's a bit more complex than that why there's a peak of interest in computers, especially handhelds in over 35's...
You get married, have children.
Observations:
Children are curious and play with stuff and break it
Children get lots of toys
You don't get to go out much
There's competition for the TV, VCR, DVD, computer etc
Why handhelds?
easy to keep to yourself - don't have to share
easy to keep out of the hands of children unlike a fixed-position computer
you take them with you everywhere, rather than leave them at home for the kids to break
you can use them in bed easily
easy to hide from your partner, he/she probably won't realise how much they cost
if you want to write s/w there's not a huge number of people doing it, so easier to make an impact
they're cool
Many of the above points are also applicable for students whose accomodation might not be permanent or secure, a handheld can be ideal.